# Copyright (c) 2011 OpenStack Foundation
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""The hosts admin extension."""

from xml.parsers import expat

from oslo.config import cfg
import webob.exc

from cinder.api import extensions
from cinder.api.openstack import wsgi
from cinder.api import xmlutil
from cinder import db
from cinder import exception
from cinder.i18n import _
from cinder.openstack.common import log as logging
from cinder.openstack.common import timeutils
from cinder import utils
from cinder.volume import api as volume_api


CONF = cfg.CONF

LOG = logging.getLogger(__name__)
authorize = extensions.extension_authorizer('volume', 'hosts')


class HostIndexTemplate(xmlutil.TemplateBuilder):
    def construct(self):
        root = xmlutil.TemplateElement('hosts')
        elem = xmlutil.SubTemplateElement(root, 'host', selector='hosts')
        elem.set('service-status')
        elem.set('service')
        elem.set('zone')
        elem.set('service-state')
        elem.set('host_name')
        elem.set('last-update')

        return xmlutil.MasterTemplate(root, 1)


class HostUpdateTemplate(xmlutil.TemplateBuilder):
    def construct(self):
        root = xmlutil.TemplateElement('host')
        root.set('host')
        root.set('status')

        return xmlutil.MasterTemplate(root, 1)


class HostActionTemplate(xmlutil.TemplateBuilder):
    def construct(self):
        root = xmlutil.TemplateElement('host')
        root.set('host')

        return xmlutil.MasterTemplate(root, 1)


class HostShowTemplate(xmlutil.TemplateBuilder):
    def construct(self):
        root = xmlutil.TemplateElement('host')
        elem = xmlutil.make_flat_dict('resource', selector='host',
                                      subselector='resource')
        root.append(elem)

        return xmlutil.MasterTemplate(root, 1)


class HostDeserializer(wsgi.XMLDeserializer):
    def default(self, string):
        try:
            node = utils.safe_minidom_parse_string(string)
        except expat.ExpatError:
            msg = _("cannot understand XML")
            raise exception.MalformedRequestBody(reason=msg)

        updates = {}
        for child in node.childNodes[0].childNodes:
            updates[child.tagName] = self.extract_text(child)

        return dict(body=updates)


def _list_hosts(req, service=None):
    """Returns a summary list of hosts."""
    curr_time = timeutils.utcnow()
    context = req.environ['cinder.context']
    services = db.service_get_all(context, False)
    zone = ''
    if 'zone' in req.GET:
        zone = req.GET['zone']
    if zone:
        services = [s for s in services if s['availability_zone'] == zone]
    hosts = []
    for host in services:
        delta = curr_time - (host['updated_at'] or host['created_at'])
        alive = abs(utils.total_seconds(delta)) <= CONF.service_down_time
        status = (alive and "available") or "unavailable"
        active = 'enabled'
        if host['disabled']:
            active = 'disabled'
        LOG.debug('status, active and update: %s, %s, %s' %
                  (status, active, host['updated_at']))
        hosts.append({'host_name': host['host'],
                      'service': host['topic'],
                      'zone': host['availability_zone'],
                      'service-status': status,
                      'service-state': active,
                      'last-update': host['updated_at']})
    if service:
        hosts = [host for host in hosts
                 if host["service"] == service]
    return hosts


def check_host(fn):
    """Makes sure that the host exists."""
    def wrapped(self, req, id, service=None, *args, **kwargs):
        listed_hosts = _list_hosts(req, service)
        hosts = [h["host_name"] for h in listed_hosts]
        if id in hosts:
            return fn(self, req, id, *args, **kwargs)
        else:
            message = _("Host '%s' could not be found.") % id
            raise webob.exc.HTTPNotFound(explanation=message)
    return wrapped


class HostController(wsgi.Controller):
    """The Hosts API controller for the OpenStack API."""
    def __init__(self):
        self.api = volume_api.HostAPI()
        super(HostController, self).__init__()

    @wsgi.serializers(xml=HostIndexTemplate)
    def index(self, req):
        authorize(req.environ['cinder.context'])
        return {'hosts': _list_hosts(req)}

    @wsgi.serializers(xml=HostUpdateTemplate)
    @wsgi.deserializers(xml=HostDeserializer)
    @check_host
    def update(self, req, id, body):
        authorize(req.environ['cinder.context'])
        update_values = {}
        for raw_key, raw_val in body.iteritems():
            key = raw_key.lower().strip()
            val = raw_val.lower().strip()
            if key == "status":
                if val in ("enable", "disable"):
                    update_values['status'] = val.startswith("enable")
                else:
                    explanation = _("Invalid status: '%s'") % raw_val
                    raise webob.exc.HTTPBadRequest(explanation=explanation)
            else:
                explanation = _("Invalid update setting: '%s'") % raw_key
                raise webob.exc.HTTPBadRequest(explanation=explanation)
        update_setters = {'status': self._set_enabled_status}
        result = {}
        for key, value in update_values.iteritems():
            result.update(update_setters[key](req, id, value))
        return result

    def _set_enabled_status(self, req, host, enabled):
        """Sets the specified host's ability to accept new volumes."""
        context = req.environ['cinder.context']
        state = "enabled" if enabled else "disabled"
        LOG.info(_("Setting host %(host)s to %(state)s."),
                 {'host': host, 'state': state})
        result = self.api.set_host_enabled(context,
                                           host=host,
                                           enabled=enabled)
        if result not in ("enabled", "disabled"):
            # An error message was returned
            raise webob.exc.HTTPBadRequest(explanation=result)
        return {"host": host, "status": result}

    @wsgi.serializers(xml=HostShowTemplate)
    def show(self, req, id):
        """Shows the volume usage info given by hosts.

        :param context: security context
        :param host: hostname
        :returns: expected to use HostShowTemplate.
            ex.::

                {'host': {'resource':D},..}
                D: {'host': 'hostname','project': 'admin',
                    'volume_count': 1, 'total_volume_gb': 2048}
        """
        host = id
        context = req.environ['cinder.context']
        if not context.is_admin:
            msg = _("Describe-resource is admin only functionality")
            raise webob.exc.HTTPForbidden(explanation=msg)

        try:
            host_ref = db.service_get_by_host_and_topic(context,
                                                        host,
                                                        CONF.volume_topic)
        except exception.ServiceNotFound:
            raise webob.exc.HTTPNotFound(explanation=_("Host not found"))

        # Getting total available/used resource
        # TODO(jdg): Add summary info for Snapshots
        volume_refs = db.volume_get_all_by_host(context, host_ref['host'])
        (count, sum) = db.volume_data_get_for_host(context,
                                                   host_ref['host'])

        snap_count_total = 0
        snap_sum_total = 0
        resources = [{'resource': {'host': host, 'project': '(total)',
                                   'volume_count': str(count),
                                   'total_volume_gb': str(sum),
                                   'snapshot_count': str(snap_count_total),
                                   'total_snapshot_gb': str(snap_sum_total)}}]

        project_ids = [v['project_id'] for v in volume_refs]
        project_ids = list(set(project_ids))
        for project_id in project_ids:
            (count, sum) = db.volume_data_get_for_project(context, project_id)
            (snap_count, snap_sum) = db.snapshot_data_get_for_project(
                context,
                project_id)
            resources.append(
                {'resource':
                    {'host': host,
                     'project': project_id,
                     'volume_count': str(count),
                     'total_volume_gb': str(sum),
                     'snapshot_count': str(snap_count),
                     'total_snapshot_gb': str(snap_sum)}})
            snap_count_total += int(snap_count)
            snap_sum_total += int(snap_sum)
        resources[0]['resource']['snapshot_count'] = str(snap_count_total)
        resources[0]['resource']['total_snapshot_gb'] = str(snap_sum_total)
        return {"host": resources}


class Hosts(extensions.ExtensionDescriptor):
    """Admin-only host administration."""

    name = "Hosts"
    alias = "os-hosts"
    namespace = "http://docs.openstack.org/volume/ext/hosts/api/v1.1"
    updated = "2011-06-29T00:00:00+00:00"

    def get_resources(self):
        resources = [extensions.ResourceExtension('os-hosts',
                                                  HostController(),
                                                  collection_actions={
                                                      'update': 'PUT'},
                                                  member_actions={
                                                      'startup': 'GET',
                                                      'shutdown': 'GET',
                                                      'reboot': 'GET'})]
        return resources
